ACM Prajin, a deputy NCPO chief, said Gen Prayuth's suitability for the post is apparent from his capability in taking the helm of the country's administration during the past two months.
He said he himself is not suitable for the post.
According to the interim constitution of 2014, the NCPO's membership will increase from the current seven to 15.
"So far, there has not been any suggestion of appointing anyone else to replace Gen Prayuth as NCPO chief or moving up a deputy chief to take his place," ACM Prajin said.
On the appointment of a large number of active and retired military officers to the National Legislative Assembly (NLA), ACM Prajin said this was to ensure effective implementation of the NCPO's road map.
He said despite the resignation of Gen Thawatchai Samutsakhon, the former 2nd Army chief, and Aziz Pitakkhumphol, the Chularatchamontree, as NLA members, the remaining 198 can carry out the NLA's work until more are appointed to meet the full number of 220 as stipulated by the interim charter.
ACM Prajin declined to comment when asked whether he would concurrently hold the posts of deputy prime minister and transport minister in the new cabinet yet to be appointed.